1. Field of the Invention
The present invention provides nucleotide sequences from Coryneform bacteria which code for the PtsI protein and a process for the fermentative preparation of amino acids using bacteria in which the ptsI gene is enhanced.
2. Discussion of the Background
L-Amino acids, in particular L-lysine, are used in human medicine, in the pharmaceuticals industry and in the foodstuffs industry, particularly in animal nutrition.
It is known that amino acids are prepared by fermentation from strains of Coryneform bacteria, in particular Corynebacterium glutamicum. Because of their great importance, work is constantly being undertaken to improve amino acid preparations. Improvements can relate to the fermentation means, such as stirring and supply of oxygen; the composition of the nutrient media, such as the sugar concentration during the fermentation; working up the product form, for example, using ion exchange chromatography; or by altering the intrinsic output properties of the microorganism itself.
Methods of mutagenesis and mutant selection are used to improve the output properties of microorganisms. Strains that are resistant to antimetabolites or are auxotrophic for metabolites of regulatory importance and produce amino acids may be obtained in this manner.
Methods of the recombinant DNA technique have also been employed for some years to improve Corynebacterium strains which produce L-amino acid, by amplifying individual amino acid biosynthesis genes and investigating the effect on the amino acid production.
However, there remains a critical need for improved methods of producing L-amino acids and thus for the provision of strains of bacteria producing higher amounts of L-amino acids. On a commercial or industrial scale even small improvements in the yield of L-amino acids, or the efficiency of their production, are economically significant. Prior to the present invention, it was not recognized that enhancing the ptsI gene encoding the enzyme phosphotransferase system enzyme I (PtsI) would improve L-amino acid yields.